wiring a aftermarket horn with relay

[joe 1950]

what i’m trying to do is wire up a aftermarket spartan horn with a relay in a 1935 ford pickup i’ve wired relays in other vehicles i no how they work but i can’t get the horn button to ground the relay truck has one original horn that works but on this system the voltage passes through the horn to energize the coil and is grounded through the button need. wiring diagram for the aftermarket witch didn’t get with it thanks for any help i can get

[Bored&Stroked]

If the relay is energized by grounding one pole of it, then it should work just fine. What type of relay do you have? Do you have a part number?

[joe 1950]

the relay works fine i’ve bench tested it what i can’t get is the horn button to activate the relay by grounding it when pushed

[40cpe]

I think you need to permanently ground the relay terminal and provide the power to activate the relay through the horn button.

[joe 1950]

40 cpe i totally understand what you’re saying the relay has 3 terminal on it. Horn. Bat. Switch . so if i ground the switch terminal then the relay will be energize full time the truck has one original horn that works there’s power on both terminals one is bright and one dim when i activate the horn button the dim one goes out so i assume that would be the ground side those horns are wired hot all time just saying

[Bored&Stroked]

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So, it works when you just manually jump the 'Switch' terminal to ground? But, when you attempt to use the horn button to supply the ground, it does not work? If so, then use an OHM meter and connect one lead to the frame and the other to the horn wire and see if the button is working correctly. You should see continuity when pressing the button.

[petehoovie]

Originally Posted by joe 1950

40 cpe i totally understand what you’re saying the relay has 3 terminal on it. Horn. Bat. Switch . so if i ground the switch terminal then the relay will be energize full time the truck has one original horn that works there’s power on both terminals one is bright and one dim when i activate the horn button the dim one goes out so i assume that would be the ground side those horns are wired hot all time just saying

[Bored&Stroked]

Originally Posted by 40cpe

I think you need to permanently ground the relay terminal and provide the power to activate the relay through the horn button.

FYI - there is no power through the horn button - it goes to ground. So the relay needs to be normally open and actuated when the "switch" side sees ground.

[JayChicago]

Do solenoid coils care about polarity?

If the relay's solenoid coil is designed for the typical negative ground, but on our cars its positive ground, electrons are flowing backwards. Would that make the solenoid switch magnet pull backwards, opening the contacts?

[JayChicago]

If the relay is designed for 12 volt, maybe 6 volts is not strong enough to pull in the relay's solenoid switch?

Edit:
Just realized you did a bench test and the relay worked. So that dis-proves both my thoughts above. Nevermind!

[joe 1950]

I want to thank all of you for your help the wiring diagram was very helpful i figured it out and got the relay to work with the horn button the new aftermarket market horn would work but sound was terrible so come to adjust the screw for tone only to find it was stripped out my buddy had this horn about 10 years ago so i think the warranty is off but everything works as it should thanks again